| 1. |
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| 2. |
- Dyal Ukabhai, K., et al.
(författare)
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Formation of Ti2Cu in Ti-Cu Alloys
- 2022
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Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 43:3, s. 332-344
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Tidskriftsartikel (refereegranskat)abstract
- One of the major issues with dental implants is failure due to bacterial infection, and additions of copper are known to improve the antimicrobial properties of Ti alloys. There are inconsistencies in the Ti rich area of the Cu-Ti binary phase diagram, hence the need to find out if Ti2Cu or Ti3Cu is formed, and to identify the type of formation of Ti2Cu. Four alloys: 20, 33, 40 and 50 Cu (mass%) were produced by arc melting and studied using SEM, XRD and DSC. The reactions were derived, and the temperatures of the reactions were determined by DSC. The formation of Ti2Cu is congruent, and no Ti3Cu was found.
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| 3. |
- Halliday, Alison, et al.
(författare)
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10-year stroke prevention after successful carotid endarterectomy for asymptomatic stenosis (ACST-1) : A multicentre randomised trial
- 2010
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 376:9746, s. 1074-1084
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Tidskriftsartikel (refereegranskat)abstract
- Background If carotid artery narrowing remains asymptomatic (ie, has caused no recent stroke or other neurological symptoms), successful carotid endarterectomy (CEA) reduces stroke incidence for some years. We assessed the long-term effects of successful CEA. Methods Between 1993 and 2003, 3120 asymptomatic patients from 126 centres in 30 countries were allocated equally, by blinded minimised randomisation, to immediate CEA (median delay 1 month, IQR 0·3-2·5) or to indefinite deferral of any carotid procedure, and were followed up until death or for a median among survivors of 9 years (IQR 6-11). The primary outcomes were perioperative mortality and morbidity (death or stroke within 30 days) and non-perioperative stroke. Kaplan-Meier percentages and logrank p values are from intention-to-treat analyses. This study is registered, number ISRCTN26156392. Findings 1560 patients were allocated immediate CEA versus 1560 allocated deferral of any carotid procedure. The proportions operated on while still asymptomatic were 89·7 versus 4·8 at 1 year (and 92·1 vs 16·5 at 5 years). Perioperative risk of stroke or death within 30 days was 3·0 (95 CI 2·4-3·9; 26 non-disabling strokes plus 34 disabling or fatal perioperative events in 1979 CEAs). Excluding perioperative events and non-stroke mortality, stroke risks (immediate vs deferred CEA) were 4·1 versus 10·0 at 5 years (gain 5·9, 95 CI 4·0-7·8) and 10·8 versus 16·9 at 10 years (gain 6·1, 2·7-9·4); ratio of stroke incidence rates 0·54, 95 CI 0·43-0·68, p<0·0001. 62 versus 104 had a disabling or fatal stroke, and 37 versus 84 others had a non-disabling stroke. Combining perioperative events and strokes, net risks were 6·9 versus 10·9 at 5 years (gain 4·1, 2·0-6·2) and 13·4 versus 17·9 at 10 years (gain 4·6, 1·2-7·9). Medication was similar in both groups; throughout the study, most were on antithrombotic and antihypertensive therapy. Net benefits were significant both for those on lipid-lowering therapy and for those not, and both for men and for women up to 75 years of age at entry (although not for older patients). Interpretation Successful CEA for asymptomatic patients younger than 75 years of age reduces 10-year stroke risks. Half this reduction is in disabling or fatal strokes. Net benefit in future patients will depend on their risks from unoperated carotid lesions (which will be reduced by medication), on future surgical risks (which might differ from those in trials), and on whether life expectancy exceeds 10 years. Funding UK Medical Research Council, BUPA Foundation, Stroke Association.
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| 4. |
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| 5. |
- Shahim, Pashtun, 1984, et al.
(författare)
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Serum neurofilament light protein predicts clinical outcome in traumatic brain injury
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Axonal white matter injury is believed to be a major determinant of adverse outcomes following traumatic brain injury (TBI). We hypothesized that measurement of neurofilament light protein (NF-L), a protein found in long white-matter axons, in blood samples, may serve as a suitable biomarker for neuronal damage in TBI patients. To test our hypotheses, we designed a study in two parts: i) we developed an immunoassay based on Single molecule array technology for quantification of NF-L in blood, and ii) in a proof-of-concept study, we tested our newly developed method on serial serum samples from severe TBI (sTBI) patients (n = 72) and controls (n = 35). We also compared the diagnostic and prognostic utility of NF-L with the established blood biomarker S100B. NF-L levels were markedly increased in sTBI patients compared with controls. NF-L at admission yielded an AUC of 0.99 to detect TBI versus controls (AUC 0.96 for S100B), and increased to 1.00 at day 12 (0.65 for S100B). Importantly, initial NF-L levels predicted poor 12-month clinical outcome. In contrast, S100B was not related to outcome. Taken together, our data suggests that measurement of serum NF-L may be useful to assess the severity of neuronal injury following sTBI.
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| 6. |
- Dalarsson, Mariana, et al.
(författare)
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Gradient index metamaterial with arbitrary loss factors in RHM and LHM media : The case of constant impedance throughout the structure
- 2012
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Ingår i: PIERS 2012 Moscow. - : Electromagnetics Academy. - 9781934142226 ; , s. 1390-1394
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Konferensbidrag (refereegranskat)abstract
- The transmission and reflection properties of lossy structures involving left-handed materials with graded permittivity and permeability have been investigated. We present an exact analytical solution to Helmholtz' equation for a lossy case with the graded both real and imaginary parts of permittivity and permeability profile changing according to a hyperbolic tangent function along the direction of propagation. This allows for different loss factors in the two media. The expressions and graphical results for the field intensity along the graded structure are presented. The analytical solution is validated by a dispersive numerical model of lossy metamaterials that uses a transmission line matrix method based on Z-transforms, where a close agreement between the analytic and numerical results is obtained.
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| 7. |
- Dalarsson, Mariana, et al.
(författare)
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Lossy gradient index transmission optics with arbitrary periodic permittivity and permeability and constant impedance throughout the structure
- 2012
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Ingår i: Journal of Optics. - : IOP Publishing. - 2040-8978 .- 2040-8986. ; 14:6, s. 065102-
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Tidskriftsartikel (refereegranskat)abstract
- A remarkably simple exact analytical solution is obtained for the electromagnetic field distribution across infinite metamaterial-containing composites with any arbitrary periodic variation of complex effective permittivity and permeability for the case of constant impedance across the structure. Arbitrary temporal dispersion and losses are allowed and the model is generally applicable to different inhomogeneous and anisotropic media simultaneously containing positive and negative refractive index constituents, as long as the effective medium approximation remains valid. The analytical solution is validated by a dispersive numerical model of lossy metamaterials that uses a transmission line matrix method based on Z-transforms, where a close agreement between the analytic and numerical results is obtained.
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| 8. |
- Dalarsson, Mariana, et al.
(författare)
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Lossy transmision with arbitrary gradient permittivity and permeability and constant impedance throughout the structure
- 2013
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Ingår i: 2013 11th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services, TELSIKS 2013. - : IEEE. - 9781479909025 ; , s. 25-28
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Konferensbidrag (refereegranskat)abstract
- We present a remarkably simple exact analytical solution for the electromagnetic field distribution across an infinite metamaterial composite with an arbitrary graded variation of complex effective permittivity and permeability for the case of constant impedance across the structure. Arbitrary temporal dispersion and losses are allowed and the model is generally applicable to different inhomogeneous and anisotropic media simultaneously containing positive and negative refractive index constituents, as long as the effective medium approximation remains valid. The analytical solution is validated by a dispersive numerical model of lossy metamaterials that uses a transmission line matrix method based on Z-transforms, where a close agreement between the analytic and numerical results is obtained.
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| 9. |
- Dekki, N, et al.
(författare)
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Type 1 diabetic serum interferes with pancreatic beta-cell Ca2+-handling
- 2007
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Ingår i: Bioscience reports. - : Portland Press Ltd.. - 0144-8463 .- 1573-4935. ; 27:6, s. 321-326
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to clarify the frequency of patients with type 1 diabetes that have serum that increases pancreatic β-cell cytoplasmic free Ca2+ concentration, [Ca2+]i, and if such an effect is also present in serum from first-degree relatives. We also studied a possible link between the serum effect and ethnic background as well as presence of autoantibodies. Sera obtained from three different countries were investigated as follows: 82 Swedish Caucasians with newly diagnosed type 1 diabetes, 56 Americans with different duration of type 1 diabetes, 117 American first-degree relatives of type 1 diabetic patients with a mixed ethnic background and 31 Caucasian Finnish children with newly diagnosed type 1 diabetes. Changes in [Ca2+]i, upon depolarization, were measured in β-cells incubated overnight with sera from type 1 diabetic patients, first-degree relatives or healthy controls. Our data show that there is a group constituting approximately 30% of type 1 diabetic patients of different gender, age, ethnic background and duration of the disease, as well as first-degree relatives of type 1 diabetic patients, that have sera that interfere with pancreatic β-cell Ca2+-handling. This effect on β-cell [Ca2+]i could not be correlated to the presence of autoantibodies. In a defined subgroup of patients with type 1 diabetes and first-degree relatives a defect Ca2+-handling may aggravate development of β-cell destruction.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Govsyeyev, Nicholas, et al.
(författare)
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Rivaroxaban in Patients with Symptomatic Peripheral Artery Disease after Lower Extremity Bypass Surgery with Venous and Prosthetic Conduits
- 2023
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Ingår i: Journal of Vascular Surgery. - : Elsevier. - 0741-5214 .- 1097-6809. ; 77:4, s. 1107-1118.e2
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Patients with peripheral artery disease (PAD) requiring lower extremity revascularization (LER) are at high risk of adverse limb and cardiovascular events. VOYAGER PAD demonstrated that rivaroxaban significantly reduced this risk with an overall favorable net benefit in patients undergoing surgical revascularization; however, the efficacy and safety in those treated by surgical bypass including stratified by bypass conduit (venous or prosthetic) has not been described.METHODS: In the VOYAGER PAD trial, patients with PAD after surgical and endovascular infrainguinal LER were randomized to rivaroxaban 2.5 mg twice daily or placebo and followed for a median of 28 months. The primary endpoint was a composite of acute limb ischemia (ALI), major amputation of vascular etiology, myocardial infarction, ischemic stroke, or cardiovascular death. The principal safety outcome was Thrombolysis in Myocardial Infarction (TIMI) major bleeding. Index procedure details including conduit type (venous or prosthetic) were collected at baseline.RESULTS: Among 6564 randomized, 2185 (33%) underwent surgical LER. Of these, surgical bypass was performed in 1448 (66%), using prosthetic conduit in 773 (53%) and venous in 646 (45%). Adjusting for baseline differences and anatomic factors, the risk for unplanned limb revascularization in the placebo arm was 2.5-fold higher for those receiving prosthetic versus venous conduits (adjHR 2.53, 95% CI 1.65-3.90; p<0.001) while the risk for ALI was 3 times greater (adjHR 3.07, 95% CI 1.84-5.11; p<0.001). Rivaroxaban reduced the primary outcome in patients treated with bypass surgery (HR 0.78, 95% CI 0.62-0.98) with consistent benefits in those receiving venous (HR 0.66, 95% CI 0.49-0.96) and prosthetic (HR 0.87, 95% CI 0.66-1.15) conduits (pinteraction 0.254). In the overall trial, TIMI major bleeding was increased with rivaroxaban; however, numbers in those treated with bypass surgery were low (5 with rivaroxaban, 9 with placebo, HR 0.55, 95% CI 0.18-1.65) and not powered to show statistical significance.CONCLUSIONS: Surgical bypass with prosthetic conduit is associated with significantly higher rates of major adverse limb events relative to venous conduits even after adjusting for patient and anatomic characteristics. Adding rivaroxaban 2.5 mg twice daily to aspirin or dual antiplatelet therapy significantly reduces this risk, increases bleeding, but has a favorable benefit risk in patients treated with bypass surgery and regardless of conduit type. Rivaroxaban should be considered after lower extremity bypass for symptomatic PAD to reduce ischemic complications of the heart, limb, and brain.
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| 15. |
- Hess, C. N., et al.
(författare)
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A Structured Review of Antithrombotic Therapy in Peripheral Artery Disease With a Focus on Revascularization A TASC (InterSociety Consensus for the Management of Peripheral Artery Disease) Initiative
- 2017
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Ingår i: Circulation. - : Ovid Technologies (Wolters Kluwer Health). - 0009-7322 .- 1524-4539. ; 135:25, s. 2534-2555
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Tidskriftsartikel (refereegranskat)abstract
- Peripheral artery disease affects >200 million people worldwide and is associated with significant limb and cardiovascular morbidity and mortality. Limb revascularization is recommended to improve function and quality of life for symptomatic patients with peripheral artery disease with intermittent claudication who have not responded to medical treatment. For patients with critical limb ischemia, the goals of revascularization are to relieve pain, help wound healing, and prevent limb loss. The baseline risk of cardiovascular and limb-related events demonstrated among patients with stable peripheral artery disease is elevated after revascularization and related to atherothrombosis and restenosis. Both of these processes involve platelet activation and the coagulation cascade, forming the basis for the use of antiplatelet and anticoagulant therapies to optimize procedural success and reduce postprocedural cardiovascular risk. Unfortunately, few high-quality, randomized data to support use of these therapies after peripheral artery disease revascularization exist, and much of the rationale for the use of antiplatelet agents after endovascular peripheral revascularization is extrapolated from percutaneous coronary intervention literature. Consequently, guideline recommendations for antithrombotic therapy after lower limb revascularization are inconsistent and not always evidence-based. In this context, the purpose of this structured review is to assess the available randomized data for antithrombotic therapy after peripheral arterial revascularization, with a focus on clinical trial design issues that may affect interpretation of study results, and highlight areas that require further investigation.
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| 16. |
- Hess, Connie N., et al.
(författare)
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A Structured Review of Antithrombotic Therapy in Peripheral Artery Disease with a Focus on Revascularization : A TASC (InterSociety Consensus for the Management of Peripheral Artery Disease) Initiative
- 2017
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Ingår i: Circulation. - 0009-7322. ; 135:25, s. 2534-2555
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Forskningsöversikt (refereegranskat)abstract
- Peripheral artery disease affects >200 million people worldwide and is associated with significant limb and cardiovascular morbidity and mortality. Limb revascularization is recommended to improve function and quality of life for symptomatic patients with peripheral artery disease with intermittent claudication who have not responded to medical treatment. For patients with critical limb ischemia, the goals of revascularization are to relieve pain, help wound healing, and prevent limb loss. The baseline risk of cardiovascular and limb-related events demonstrated among patients with stable peripheral artery disease is elevated after revascularization and related to atherothrombosis and restenosis. Both of these processes involve platelet activation and the coagulation cascade, forming the basis for the use of antiplatelet and anticoagulant therapies to optimize procedural success and reduce postprocedural cardiovascular risk. Unfortunately, few high-quality, randomized data to support use of these therapies after peripheral artery disease revascularization exist, and much of the rationale for the use of antiplatelet agents after endovascular peripheral revascularization is extrapolated from percutaneous coronary intervention literature. Consequently, guideline recommendations for antithrombotic therapy after lower limb revascularization are inconsistent and not always evidence-based. In this context, the purpose of this structured review is to assess the available randomized data for antithrombotic therapy after peripheral arterial revascularization, with a focus on clinical trial design issues that may affect interpretation of study results, and highlight areas that require further investigation.
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| 17. |
- Hess, C. N., et al.
(författare)
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Acute Limb Ischemia in Peripheral Artery Disease Insights From EUCLID
- 2019
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Ingår i: Circulation. - : Ovid Technologies (Wolters Kluwer Health). - 0009-7322 .- 1524-4539. ; 140:7, s. 556-565
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Tidskriftsartikel (refereegranskat)abstract
- Background: Acute limb ischemia (ALI) is an important clinical event and an emerging cardiovascular clinical trial outcome. Risk factors for and outcomes after ALI have not been fully evaluated. Methods: EUCLID (Examining Use of Ticagrelor in Peripheral Artery Disease) randomized patients with peripheral artery disease to ticagrelor versus clopidogrel. Enrollment criteria included an ankle-brachial index <= 0.80 or previous lower extremity revascularization. Patients were grouped according to the primary outcome, postrandomization ALI hospitalization. Baseline factors associated with ALI were identified using Cox proportional hazards modeling. Models with ALI hospitalization as a time-dependent covariate were developed for secondary outcomes of major adverse cardiovascular events (myocardial infarction, cardiovascular death, ischemic stroke), all-cause mortality, and major amputation. Results: Among 13 885 patients, 1.7% (n=232) had 293 ALI hospitalizations (0.8 per 100 patient-years). Patients with versus without ALI were younger and more often had previous peripheral revascularization and lower baseline ankle-brachial index. Treatment during ALI hospitalization included endovascular revascularization (39.2%, n=115), surgical bypass (24.6%, n=72), and major amputation (13.0%, n=38). After multivariable adjustment, any previous peripheral revascularization (Hazard Ratio [HR] 4.7, 95% CI 3.3-6.8, P<0.01), baseline atrial fibrillation (HR 1.8, 95% CI 1.1-3.2, P=0.03), and baseline ankle-brachial index <= 0.60 (HR 1.3 per 0.10 decrease, 95% CI 1.1-1.5, P<0.01) were associated with higher ALI risk. Older age (HR 0.8 per 10-year increase, 95% CI 0.7-1.0, P=0.02) and baseline statin use (HR 0.7, 95% CI 0.5-0.9, P<0.01) were associated with lower risk for ALI. There was no relationship between randomized treatment to ticagrelor or clopidogrel and ALI. Among patients with previous revascularization, surgical versus endovascular procedures performed more than 6 months prior were associated with ALI (adjusted HR 2.63, 95% CI 1.75-3.96). In the overall population, ALI hospitalization was associated with subsequent MACE (adjusted HR 1.4, 95% CI 1.0-2.1, P=0.04), all-cause mortality (adjusted HR 3.3, 95% CI 2.4-4.6, P<0.01), and major amputation (adjusted HR 34.2, 95% CI 9.7-20.8, P<0.01). Conclusions: Previous peripheral revascularization, baseline atrial fibrillation, and lower ankle-brachial index identify peripheral artery disease patients at heightened risk for ALI, an event associated with subsequent cardiovascular and limb-related morbidity and mortality.
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| 18. |
- Khotyaintsev, Yu, V, et al.
(författare)
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Electron Heating by Debye-Scale Turbulence in Guide-Field Reconnection
- 2020
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 124:4
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Tidskriftsartikel (refereegranskat)abstract
- We report electrostatic Debye-scale turbulence developing within the diffusion region of asymmetric magnetopause reconnection with amoderate guide field using observations by the Magnetospheric Multiscale mission. We show that Buneman waves and beam modes cause efficient and fast thermalization of the reconnection electron jet by irreversible phase mixing, during which the jet kinetic energy is transferred into thermal energy. Our results show that the reconnection diffusion region in the presence of a moderate guide field is highly turbulent, and that electrostatic turbulence plays an important role in electron heating.
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| 19. |
- Le Contel, O., et al.
(författare)
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Lower Hybrid Drift Waves and Electromagnetic Electron Space-Phase Holes Associated With Dipolarization Fronts and Field-Aligned Currents Observed by the Magnetospheric Multiscale Mission During a Substorm
- 2017
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Ingår i: Journal of Geophysical Research - Space Physics. - : AMER GEOPHYSICAL UNION. - 2169-9380 .- 2169-9402. ; 122:12, s. 12236-12257
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Tidskriftsartikel (refereegranskat)abstract
- We analyze two ion scale dipolarization fronts associated with field-aligned currents detected by the Magnetospheric Multiscale mission during a large substorm on 10 August 2016. The first event corresponds to a fast dawnward flow with an antiparallel current and could be generated by the wake of a previous fast earthward flow. It is associated with intense lower hybrid drift waves detected at the front and propagating dawnward with a perpendicular phase speed close to the electric drift and the ion thermal velocity. The second event corresponds to a flow reversal: from southwward/dawnward to northward/duskward associated with a parallel current consistent with a brief expansion of the plasma sheet before the front crossing and with a smaller lower hybrid drift wave activity. Electromagnetic electron phase-space holes are detected near these low-frequency drift waves during both events. The drift waves could accelerate electrons parallel to the magnetic field and produce the parallel electron drift needed to generate the electron holes. Yet we cannot rule out the possibility that the drift waves are produced by the antiparallel current associated with the fast flows, leaving the source for the electron holes unexplained.
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| 20. |
- Masia, NDE, et al.
(författare)
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Corrosion performance of Ti-Cu alloys targeted for biomedical applications
- 2022
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Ingår i: Suid-Afrikaanse tydskrif vir natuurwetenskap en tegnologie. - : Medpharm Publications. - 0254-3486 .- 2222-4173. ; 40:1, s. 244-250
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Tidskriftsartikel (refereegranskat)abstract
- The Thermo-Calc™ program and TTTI3 database were used to predict the phases in Ti-Cu with 5, 25, and 40 wt% Cu. Based on the predicted results, experimental work was conducted and the Ti-Cu alloys were produced in a button arc furnace, and characterised in the as-cast and the annealed condition (900°C) followed by water quenching. Microstructures and compositions were determined using an electron probe micro-analyser, and the phases were identified by X-ray diffraction. The corrosion performance was measured by potentiodynamic polarisation in a phosphate buffered saline solution at 37 °C at 7.4 pH while purging with nitrogen gas. The Ti-5Cu and Ti-25Cu alloys comprised (αTi) and Ti2Cu phases, the Ti-40Cu alloy comprised Ti2Cu and TiCu. Although the addition of copper decreased the corrosion performance by down to 75%, the corrosion rates were still within the acceptable range (0.02-0.13 mm/y) for biocompatibility of metallic implants. Annealing at 900 °C did not improve the corrosion performance.
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| 21. |
- Norgren, Magnus, et al.
(författare)
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Physiochemical differences between dissolved and precipitated Kraft lignin fragments as determined by PFG NMR, CZE and quantitative UV spectrophotometry
- 2001
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Ingår i: Journal of Pulp and Paper Science (JPPS). - 0826-6220. ; 27:11, s. 359-363
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Tidskriftsartikel (refereegranskat)abstract
- A combination of analytical techniques, specifically capillary zone electrophoresis, H-1 pulsed-field gradient nuclear magnetic resonance se (diffusion measurements and quantitative UV spectrophotometric measurements, was used to investigate physicochemical differences between dissolved and precipitated kraft lignin (KL)fragments, obtained from the same sample. Precipitation was induced by heating alkaline (pOH4)Indulin AT solutions, containing various concentrations of NaCl (0.20-1.0 mol/L), at 75 degreesC. Depending on the salt concentration in the samples, different amounts of KL were precipitated. The KL precipitated at the lowest NaCl concentrations was found to consist of the largest lignin fragments whereas, at high NaCl concentrations, the KL fragments in the supernatants were found to be of comparably lower mean molecular weights. From the outcome of the investigation, it was found that the combination of analytical techniques used provides the possibility of collecting important information about physicochemical characteristics related to the solution behaviour of industrial lignins.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Toledo-Redondo, S., et al.
(författare)
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Solar Wind-Magnetosphere Coupling During Radial Interplanetary Magnetic Field Conditions : Simultaneous Multi-Point Observations
- 2021
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Ingår i: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 126:11
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Tidskriftsartikel (refereegranskat)abstract
- In-situ spacecraft missions are powerful assets to study processes that occur in space plasmas. One of their main limitations, however, is extrapolating such local measurements to the global scales of the system. To overcome this problem at least partially, multi-point measurements can be used. There are several multi-spacecraft missions currently operating in the Earth's magnetosphere, and the simultaneous use of the data collected by them provides new insights into the large-scale properties and evolution of magnetospheric plasma processes. In this work, we focus on studying the Earth's magnetopause (MP) using a conjunction between the Magnetospheric Multiscale and Cluster fleets, when both missions skimmed the MP for several hours at distant locations during radial interplanetary magnetic field (IMF) conditions. The observed MP positions as a function of the evolving solar wind conditions are compared to model predictions of the MP. We observe an inflation of the magnetosphere (similar to 0.7 R-E), consistent with magnetosheath pressure decrease during radial IMF conditions, which is less pronounced on the flank (<0.2 R-E). There is observational evidence of magnetic reconnection in the subsolar region for the whole encounter, and in the dusk flank for the last portion of the encounter, suggesting that reconnection was extending more than 15 R-E. However, reconnection jets were not always observed, suggesting that reconnection was patchy, intermittent or both. Shear flows reduce the reconnection rate up to similar to 30% in the dusk flank according to predictions, and the plasma beta enhancement in the magnetosheath during radial IMF favors reconnection suppression by the diamagnetic drift.
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| 26. |
- Toledo-Redondo, S., et al.
(författare)
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Statistical Observations of Proton-Band Electromagnetic Ion Cyclotron Waves in the Outer Magnetosphere: Full Wavevector Determination
- 2024
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Ingår i: Journal of Geophysical Research - Space Physics. - : John Wiley and Sons Inc. - 2169-9380 .- 2169-9402. ; 129:5
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Tidskriftsartikel (refereegranskat)abstract
- Electromagnetic Ion Cyclotron (EMIC) waves mediate energy transfer from the solar wind to the magnetosphere, relativistic electron precipitation, or thermalization of the ring current population, to name a few. How these processes take place depends on the wave properties, such as the wavevector and polarization. However, inferring the wavevector from in-situ measurements is problematic since one needs to disentangle spatial and time variations. Using 8 years of Magnetospheric Multiscale (MMS) mission observations in the dayside magnetosphere, we present an algorithm to detect proton-band EMIC waves in the Earth's dayside magnetosphere, and find that they are present roughly 15% of the time. Their normalized frequency presents a dawn-dusk asymmetry, with waves in the dawn flank magnetosphere having larger frequency than in the dusk, subsolar, and dawn near subsolar region. It is shown that the observations are unstable to the ion cyclotron instability. We obtain the wave polarization and wavevector by comparing Single Value Decomposition and Ampere methods. We observe that for most waves the perpendicular wavenumber (k⊥) is larger than the inverse of the proton gyroradius (ρi), that is, k⊥ρi > 1, while the parallel wavenumber is smaller than the inverse of the ion gyroradius, that is, k‖ρi < 1. Left-hand polarized waves are associated with small wave normal angles (θBk < 30°), while linearly polarized waves are associated with large wave normal angles (θBk > 30°). This work constitutes, to our knowledge, the first attempt to statistically infer the full wavevector of proton-band EMIC waves observed in the outer magnetosphere.
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| 27. |
- Vaivads, Andris, et al.
(författare)
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Turbulence Heating ObserveR - satellite mission proposal
- 2016
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Ingår i: JOURNAL OF PLASMA PHYSICS. - 0022-3778. ; 82
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Tidskriftsartikel (refereegranskat)abstract
- The Universe is permeated by hot, turbulent, magnetized plasmas. Turbulent plasma is a major constituent of active galactic nuclei, supernova remnants, the intergalactic and interstellar medium, the solar corona, the solar wind and the Earth's magnetosphere, just to mention a few examples. Energy dissipation of turbulent fluctuations plays a key role in plasma heating and energization, yet we still do not understand the underlying physical mechanisms involved. THOR is a mission designed to answer the questions of how turbulent plasma is heated and particles accelerated, how the dissipated energy is partitioned and how dissipation operates in different regimes of turbulence. THOR is a single-spacecraft mission with an orbit tuned to maximize data return from regions in near-Earth space - magnetosheath, shock, foreshock and pristine solar wind - featuring different kinds of turbulence. Here we summarize the THOR proposal submitted on 15 January 2015 to the 'Call for a Medium-size mission opportunity in ESAs Science Programme for a launch in 2025 (M4)'. THOR has been selected by European Space Agency (ESA) for the study phase.
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| 29. |
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